| Message ID | 20201014075048.15473-1-qiang.zhang@windriver.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] kthread_worker: Prevent queuing delayed work from timer_fn when it is being canceled | expand |
On Wed 2020-10-14 15:50:48, Zqiang wrote: > There is a small race window when a delayed work is being canceled and > the work still might be queued from the timer_fn: > > CPU0 CPU1 > kthread_cancel_delayed_work_sync() > __kthread_cancel_work_sync() > __kthread_cancel_work() > work->canceling++; > kthread_delayed_work_timer_fn() > kthread_insert_work(); > > BUG: kthread_insert_work() should not get called when work->canceling > is set. > > Cc: <stable@vger.kernel.org> > Reviewed-by: Petr Mladek <pmladek@suse.com> > Acked-by: Tejun Heo <tj@kernel.org> > Signed-off-by: Zqiang <qiang.zhang@windriver.com> Andrew, are you going to take this patch with -mm tree, please? I think that you usually take the changes in kthread.c. Best Regards, Petr
diff --git a/kernel/kthread.c b/kernel/kthread.c index 3edaa380dc7b..85a2c9b32049 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -897,7 +897,8 @@ void kthread_delayed_work_timer_fn(struct timer_list *t) /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); - kthread_insert_work(worker, work, &worker->work_list); + if (!work->canceling) + kthread_insert_work(worker, work, &worker->work_list); raw_spin_unlock_irqrestore(&worker->lock, flags); }
There is a small race window when a delayed work is being canceled and the work still might be queued from the timer_fn: CPU0 CPU1 kthread_cancel_delayed_work_sync() __kthread_cancel_work_sync() __kthread_cancel_work() work->canceling++; kthread_delayed_work_timer_fn() kthread_insert_work(); BUG: kthread_insert_work() should not get called when work->canceling is set. Cc: <stable@vger.kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Zqiang <qiang.zhang@windriver.com> --- v1->v2->v3: Change the description of the problem and add 'Reviewed-by' tags. v3->v4: Add 'stable' and 'Acked-by' tags. kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)